AB Standard (New York City Subway car)

The BMT AB Standards were slowly retired in the 1960s and replaced by R27s, R30s, R32s, R38s, R40s, and R42s. Retirement began with the trailer cars, progressed to older motor cars that were not overhauled, and finally progressed to the rest of the fleet. The last of the cars were retired from passenger service in 1969, making a final run on the Myrtle–Chambers Line. The 1969 date meant that the oldest of the cars had lasted for over 50 years in service, a remarkable amount of time for a New York subway car.

Following their removal from service, all but five AB Standards were scrapped. The five cars that were not scrapped have been preserved:

• Car 2204 has been preserved by the New York Transit Museum in Brooklyn, NY. However, it is currently not operational.
• Cars 2390, 2391 and 2392 have been preserved by Railway Preservation Corp. They were restored to operating condition in 2015 and have operated on New York Transit Museum-sponsored excursions since then.
• Car 2775 has been preserved by the Shore Line Trolley Museum in East Haven, Connecticut. However, it is not in operating condition, due to a flood at the museum site.

The Standards, when ordered, were a noticeable upgrade in the quality of New York's urban transportation. Their longer (67 feet) and wider size (10 feet) distinguished them from smaller IRT subway cars. There would be more room in each car and more space for seats. Unlike the IRT cars, end side doors were offset from the ends of the cars to aid better passenger flow. This design is covered under U.S. Patent 1,142,263, with Mr. William S. Menden (chief engineer, and later general manager of the BRT) as the inventor. In addition, there was also a set of center side doors, making for a total of three sets of doors per side. Each door set consisted of two leaves separated by a center post, which allowed more than one person to use it at once. This arrangement proved superior to all previous designs.

The cars were built with a very strong frame that utilized truss construction and allowed thin metal to be used for the side plating. This made the Standards, foot for foot, lighter than similar all-steel IRT subway cars, but with a body twice as strong. Therefore, Standards were considerably safer than any previous design, as they would not telescope in a collision. The strength of the design proved itself over and over again. Even in the 1960s, when the Standards were at or approaching 50 years of age, a couple of cars were involved in minor yard collisions with newer cars. Yet in each case, the Standard appeared to have gotten the better of the collision afterward.

Motorized Standards (motor cars 2000–2899) were built with 2 "maximum traction" type trucks where wheels closest to the center of the car were 34¹/₄ inches in diameter, while wheels closest to the ends of the car were just 31 inches in diameter. The motors were attached to the axles that bore the larger wheels. This design was believed to better distribute the car's weight to provide the best adhesion between the wheels and the rails to prevent wheelslip. Unpowered Standards (trailer cars 4000–4049) used more conventional trucks where all wheels were 31 inches in diameter.

Seating was designed to be comfortable and spacious. The Standards had short rattan benches arranged in both transverse (forward- or rear-facing) and longitudinal (sideways-facing) positions. Two to three people could fit comfortably on each bench. This gave each rider more legroom and personal space. Supplemental seats located by each side door could be folded down for rider use at a conductor's discretion. When lowered, these seats would block side door leaves, so they were protected by lock to ensure only a conductor could lower them. Under regular conditions, 78 seats were available for riders in each car. During the 1950s, many (but not all) of the rattan seats were replaced by sprung leather or a plastic compound (velon) that replicated the feel of rattan.

For standees, the cars featured four poles by each side door and small handles on the ends of transverse seats. Due to higher than anticipated ridership, metal straps were added above longitudinal seats to improve standee accommodations in 1919–1920. All orders of Standards delivered later (cars 2600–2899, 4000–4049) came with metal straps already in place. During the late 1930s, many (but not all) of the cars saw the metal straps replaced with horizontal steel bars. These accommodated even more riders than the straps had, further improving the cars. With the earlier ACF built cars, all but around 93 of these cars underwent this conversion; of the later Pressed Steel cars, just under half were converted.

As delivered, the Standards were particularly luxurious for a subway car. Each window came with a shade that could be drawn down to block out sunlight, or raised if a rider desired more natural light. Soft white glass globes served as enclosures for the car's incandescent lighting, to soften the harsh glare of the bulbs and redistribute light evenly throughout the car. However, the globes were ultimately removed from the cars between 1925 and 1927 and the shades between 1927 and 1938.

During the winter months, electric heaters under the seats provided plenty of heat. P. Smith heaters were used on cars 2400–2599 and a Gold Car Heating model for the rest of the fleet. In warmer weather, vents in the roof accommodated the influx of fresh air from outside the car. Three different vent types were used on Standards: grill type (2000–2499), box type (2500–2599), and clerestory type (2600–2899, 4000–4049). In addition, riders could open the drop sash side windows for extra ventilation. Initially made from wood (2000–2599), on later cars they were brass (2600–2899, 4000–4049). After early complaints about the summer warmth of the cars, ceiling paddle fans were added during the 1919–1920 modifications. Later Standards came already equipped with fans.

The Standards introduced interior conductor's controls. Now a conductor could stand inside rather than outside and between cars when operating the doors. The button board controls only worked if the conductor activated the board by key. This prevented tampering or error. As mentioned above, each car as delivered required its own conductor to operate doors. During the 1919–20 modifications, the Standards were unitized into new arrangements (see letter designations below) and converted to allow one conductor to control an entire train's doors. This made operation of the cars more efficient, and reduced labor costs.

Like all previously designed subway cars, Standards featured end storm doors for riders to pass between cars. However, due to the car's longer 67-foot length and resultant overhang, crossing between cars was dangerous, particularly on curves. Therefore, storm doors were kept locked on Standards, although in emergencies, they could be opened pneumatically by the conductor from the button board. For emergencies, the cars also featured emergency brake cords like other subway cars, but added an emergency alarm which could be activated to notify the train crew in case of emergency.

Electric tail lights and running lights were introduced to the subway with the Standards. Low running lights would display white at the front of the train, while tail lights displayed red in the rear. The lights adjusted automatically depending on the train's direction of travel. This was in contrast to the IRT practice of using kerosene lamps at the ends of trains, which had to be physically changed over when the train reversed direction at a terminal. At the time the Standards were delivered, the white running lights were deemed sufficient for lighting tunnels. However, during the 1950s, the New York City Subway made a system wide shift to sealed beam headlights to improve safety. Therefore, the Standards that received overhaul from 1958 to 1960 (cars 2400–2799 and 2899) received sealed beams.

Coupling and uncoupling of trains were simplified by new automatic couplers. The new WABCO couplers automatically made and broke electric and air connections as trains were coupled or uncoupled. This reduced the amount of work for train crews during the process. For example, IRT crews had to physically connect or disconnect high voltage jumper cables when coupling or uncoupling their trains. BRT/BMT crews on Standards did not. The only jumper a Standard crew would ever have to connect or disconnect was the 9 point low voltage jumper introduced with the 1919–1920 modifications. Coupling and uncoupling, therefore, were much simpler on Standards than on equipment that came before them.

The Standards also introduced the rollsign to the New York City Subway, an innovation that would be repeated on many other rolling stock orders. Older cars had metal signs which had to be physically removed and replaced to change. Rollsigns simplified the process by allowing train crews to update the sign's display by merely turning a hand crank (which would later be replaced with an allen wrench to prevent tampering in later rolling stock). Early Standards (cars 2000–2499) had the rollsigns installed in the windows behind side door pockets, while later Standards placed them in the upper half of side windows for better visibility.

Low Voltage propulsion control was coming into style around the time the earliest Standards were being delivered. Therefore, it was no surprise the Standards arrived with the feature. On earlier high voltage propulsion control systems, 600 volts ran through the motorman's control stand, as well as through the train via the use of jumpers between cars. This had to be the case to make the electrical contacts to allow all of the motor cars of a train to draw power in a synchronized effort from the Third rail. However, this could be dangerous for motormen and shop personnel alike by creating an electrocution hazard. Even unpowered trailer cars had to carry the 600 volts through these jumpers because it was necessary to pass on the voltage to motor cars behind the trailer so as to synchronize them with the lead car. However, low voltage propulsion control utilized battery voltage (32 volts) to control the train's motors. This battery voltage was what would pass through the motorman's control stand and between cars. Tractive effort throughout the train was synchronized by the battery voltage in this way. Meanwhile, each car would respond individually to the battery voltage, by moving its own 600 volt contacts to direct power obtained locally by each car directly from the third rail toward the motors. Using 32 volts to control the propulsion in this way was a much safer proposition than the 600 volts associated with the older high voltage setup. This also meant that Standards crossing onto a dead section of the third rail would not energize it by bridging the gap between it and the previous live section. This was especially beneficial to track workers who had requested the third rail power off in performing their duties. All told, Low Voltage propulsion control tremendously improved safety for train crews, shop crews, and track gangs.

One of the drawbacks of the Standard was its lack of speed. Due to its length, it was a much heavier car than the IRT steel cars of the time. But with only two motors per car at 140 horsepower each, it was actually underpowered for its size, particularly when running in a train with one or more unpowered trailers. Therefore, the top speed of the Standards was somewhat low, when compared to other rapid transit equipment that has historically run in New York City.

One other interesting note about the car's propulsion concerned the placement of the motorman's controls in the cab. Standards stuck with BRT tradition, which placed the train's controller nearest the right hand and the brake nearest the left. This was in contrast to IRT equipment, which placed the controller nearest the left and the brake nearest the right. The city-owned IND system would emulate the IRT's practice. Meanwhile, later BMT designs would replicate the Standards. Therefore, the controls in subway cars of BRT or BMT design would appear "backwards" to motormen who were acclimated primarily to IRT or IND equipment once the subways had been unified in 1940.

Braking was tremendously improved on Standards, as electropneumatic brakes synchronized the braking effort of every car in the train to provide a faster braking response. This newer type of braking, WABCO schedule AMUE, would be standard in New York's subways through the 1930s and lasted in limited quantity until as late as 1977 (when the R1-R9s, the last of the prewar cars, were retired from service). Additionally, a "Variable Load" feature automatically adjusted each car's braking effort to compensate for uneven passenger loads in different cars throughout the train. The result was a smooth, uniform braking effort that increased passenger comfort.

A handful of Standards became the first New York City subway cars to experiment with a public address system. Several cars received a loudspeaker telephone system in 1923–24 to aid conductors in making announcements. Ultimately, the experimental setup was removed by 1928, but the idea was ahead of its time. PA systems did not come into widespread use in New York's subway until the 1950s.

Standards were also the first New York City Subway equipment to experiment with cab signaling. The underlying rationale for the experiment was to allow trains to run safely at closer headways to provide more frequent service. An attempt was made in 1916 to test a GRS cab signal system using Standards. While generally working as intended, the experiment did not have staying power. The equipment necessary for its use was removed by 1918. It was not until the 1990s that a similar idea would be revisited in the subway, when MTA New York City Transit installed modern CBTC signal equipment on the BMT Canarsie Line.